In reply to Andy Turner:
Just take 1 screw gate (or one per person if you must).
30m of skinny rope (7 or 8mm).
Slack handful of wiregates and slings.
Few wires (half a set), few cams.
As others have said; pro is largely superficial, even on rock climbs up to Severe(ish), the pro will only stop you decking out, but you're probably going to bounce of the ledges!